The present invention relates to a strain gage and in particular to a strain gage used for detecting a physical quantity such as pressure, acceleration, force or load.
One of the conventional strain gages is disclosed in Japanese Patent Laid-open Print No. 56 (1981)-76001 which was published in 1981 without examination. In detail, as shown in FIG. 4, a strain gage 100 for detecting the deformation of a deformable portion 200 includes a detecting resistance 104 which is connected, in series, to an adjusting resistance menas 103 having resistances 101 and 102 both of which are connected each other in parallel. The adjusting resistance means 103 is on a rigid portion. The resistance 101 (102) has plural taps 105 (106) each of which is used as a terminal. After the strain gage 100 is mounted on the portion 200, one of terminals 105 (106) is selected for the establishment of the balance in the Wheatstone bridge.
However, in the foregoing conventional strain gages, it is very cumbersome to prepare plural taps or terminals relating to each resistance of the adjusting resistance device, which brings the enlargement of the strain gage per se.